Underwater earphone

ABSTRACT

An underwater earphone having a cylindrical casing sealed at one end by the vibratable diaphragm and at the other end by a flexible rubber diaphragm. The casing, including pole pieces and energizing coils is filled with silicone oil providing damping. This construction equalizes the pressure on either side of the vibratable diaphragm and prevents the ingress of water.

United States Patent [191 Abbagnaro Oct. 9, 1973 UNDERWATER EARPHONE[75] Inventor: Louis A. Abbagnaro, Huntington,

Conn.

[73] Assignee: The United States of America as represented by theSecretary of the Navy, Washington, D.C.

[22] Filed: Mar. 8, 1972 [21] Appl. No.: 232,800

[52] US. Cl. 340/14, 340/5 T, 340/8 LF, 340/8 PC [51] Int. Cl H04r 13/00[58] Field of Search 340/5 R, 5 T, 8 PC, 340/8 LP, 14

[56] References Cited UNITED STATES PATENTS 3,174,129 3/1965 Laughlin eta1. 340/5 T 3,351,900 11/1967 Yamamoto et a1. 340/14 X PrimaryExaminerRichard A. Farley AttorneyR. S. Sciascia et a1.

[57] ABSTRACT An underwater earphone having a cylindrical casing sealedat one end by the vibratable diaphragm and at the other end by aflexible rubber diaphragm. The casing, including pole pieces andenergizing coils is filled with silicone oil providing damping. Thisconstruction equalizes the pressure on either side of the vibratablediaphragm and prevents the ingress of water.

5 Claims, 1 Drawing Figure UNDERWATER EARPHONE BACKGROUND OF THEINVENTION This invention relates generally to underwater communicationsand, more particularly, to earphones for use underwater. The need forimproved communications in water is a prime concern to both military andcommerical factions. The increased use of selfcontained underwaterbreathing apparatus (SCUBA) has allowed the expansion of a mansunderwater exploration range at depths of several hundred feet. Majorprograms such as the U. S. Navys SEALAB, and the commercial programs forexplorations and the development of the oceans vast resources haveemerged in recent years. These programs have demonstrated the inadequacyof present diver-to-diver and diver-to-ship communications. Criticalamong the unsolved problems has been the lack of underwater earphonesfor satisfactory communications.

Past attempts to alleviate this problem have been directed to sealingthe internal structure of the earphone from the ingress of water, and toproviding a sealed transducer for bone conduction. The difficulties withthe first solution was that the ambient water pressure on the outside ofthe conventional vibrating diaphragm greatly distorted and reduced theaudio output. The second solution provided adequate response but it wasfound that all sense of directional perception and localization waslost.

SUMMARY OF THE INVENTION Accordingly, an object of the present inventionis to provide highly intelligible auditory underwater communications.

Another object of the instant invention is to provide an earphonecapable of operation at great water depths.

A further object of the invention is to provide an underwater earphonecouplable to the ear canal.

A still further object of the present invention is to provide anearphone for use underwater that produces adequate and substantiallyundistorted response.

Still another object of the instant invention is to provide an earphonefor use underwater that allows directional perception to be achieved bythe user.

Briefly, these and other objects of the present invention are attainedby the use of an earphone having a casing sealed on one side by theconventional vibrating diaphragm, and on the other side by a flexiblerubber diaphragm, and being completely filled with a silicone oil. Thisconstruction not only provides for the proper damping of the vibratingdiaphragm to produce an undistorted response; but because of theincompressibility of the silicon oil and the flexing of the rubberdiaphragm places an equalizing pressure on the inside of the vibratingdiaphragm at pressure depth. Furthermore, the presence of the siliconeoil precludes the ingress of water and protects the metal parts of theelectromagnetic circuit.

BRIEF DESCRIPTION OF THE DRAWING A more complete understanding of theinvention and many of the attendant advantages thereto will be readilyappreciated as the same becomes better understood by reference to thefollowing detailed description when considered in connection with theaccompanying drawing, wherein the figure is an isometric view, partiallycut away, of the underwater earphone.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, inthe figure, there is shown generally an underwater earphone 10 basedupon the electromagnetic principle of the moving armature type. In ashort cylindrical casing 12, made of, for example, hard rubber,phenolic, or a plastic, is mounted an apertured disc-shaped base plate14, made of a non-magnetic material such as, for example, brass,aluminum or a plastic. A plurality of fluid passages 16 are formed inthe base plate 14 in a bolt circle near the periphery thereof providingfluid communication from the front to the rear of the casing 12.

Secured to the apertured disc 14 is a pair of soft iron pole pieces 18.Affixed between these pole pieces at the rear side (right) of theearphone in any conventional manner, such as by cement or otherfastening means, is a permenent magnet 20. Each of the pole pieces onthe front side (left) is surrounded by an electromagnetic coil 22. Themagnetic circuit comprising the magnet, pole pieces, and coils, iscompleted by a vibrating diaphragm 24 made of a magnetic material suchas Vanadium Permandur. The vibrating diaphragm is spaced from the frontends of the pole pieces by an air-gap, and secured and sealed at itsperiphery to the case 12, by an apertured cap 26 and an O-ring 28. Thecoils 22 are series connected and thence connected to the signal sourcevia a cable 30 heremetically sealed by means of a gland-type fitting 32through the side of the casing 12.

The earphone is sealed at the rear of the case by a flexible rubberdiaphragm 34 compression sealed to the case by a ring 36 fastened in anysuitable manner as by screws 38. A fill hole 40 is provided in the sideof the casing 12 to completely fill the sealed casing with a siliconeoil 42 and closed by sealing screw 44.

In operation, the earphone 10 is provided with electrical signals viacable 30 to the series connected electromagnetic coils 22 which induce avarying magnetic field in the magnetic circuit comprising pole pieces 18and magnet 20, causing the diaphragm 24 to vibrate at an audiofrequency. This vibration causes movement of the silicone oil 42, whichis pumped back and forth through the apertures 16 in the disc 14 thuscreating a proper acoustical damping effect. At depths underwater theambient pressure is exerted on the outside face of the diaphragm 24tending to force it inwardly. An equal pressure, however, is transmittedto the inside face of the diaphragm through the rubber diaphragm 34 andthe incompressible silicone oil 42 flowing through the apertures 16. Asit evident the silicone oil also functions to preclude the ingress ofwater into the casing where it would otherwise corrode the metal partsand destroy the operation of the earphone.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that, within the scope of the appended claims, theinvention may be practiced otherwise than as specifically described.

I claim:

1. An earphone for use in an underwater environment comprising:

a cylindrical casing;

an electromagnetic circuit contained in said casing including;

a pair of soft iron pole pieces,

a permanent magnet affixed between the ends of said pole pieces, and

a pair of series-connected coils, each of which surrounds one of saidpair of pole pieces;

a vibratable diaphragm completing said circuit thru an air gap andsealingly secured at its periphery to the front end of said casing;

a flexible diaphragm sealedly secured at its periphery to the rear endof said casing; and

an incompressible fluid completely filling said casing, whereby anambient pressure on the face of said vibratable diaphragm iscounteracted by an equal 4. The earphone of claim 3 wherein saidimcompressible fluid comprises silicone oil.

5. The earphone of claim 4 wherein said electromagnetic circuit issecured to said casing by an apertured disc whereby flow of saidsilicone oil is permitted from the front to the rear of said casing.

1. An earphone for use in an underwater environment comprising: acylindrical casing; an electromagnetic circuit contained in said casingincluding; a pair of soft iron pole pieces, a permanent magnet affixedbetween the ends of said pole pieces, and a pair of series-connectedcoils, each of which surrounds one of said pair of pole pieces; avibratable diaphragm completing said circuit thru an air gap andsealingly secured at its periphery to the front end of said casing; aflexible diaphragm sealedly secured at its periphery to the rear end ofsaid casing; and an incompressible fluid completely filling said casing,whereby an ambient pressure on the face of said vibratable diaphragm iscounteracted by an equal and opposite pressure from the inside of saidcasing transmitted through said fluid and by said flexible diaphragm incontact with the environment.
 2. The earphone of claim 1 wherein saidvibratable diaphragm is composed of Vanadium Permandue.
 3. The earphoneof claim 2 wherein said flexible diaphragm is composed of rubber.
 4. Theearphone of claim 3 wherein said imcompressible fluid comprises siliconeoil.
 5. The earphone of claim 4 wherein said electromagnetic circuit issecured to said casing by an apertured disc whereby flow of saidsilicone oil is permitted from the front to the rear of said casing.